This relates to systems in which power converters are used to charge electronic devices, and more particularly, to systems in which power converters and electronic devices cooperate to ensure that the power converters can enter a low power sleep mode whenever possible to reduce power consumption.
Power converter circuitry can be used to convert alternating current (AC) power into direct current (DC) power. AC power is typically supplied from wall outlets and is sometimes referred to as line power. Electronic devices include circuitry that runs from DC power. The DC power that is created by an AC-to-DC power converter may be used to power an electronic device. The DC power that is created may also be used to charge a battery in an electronic device.
In some applications, AC to DC power converter circuitry may be incorporated into an electronic device. For example, desktop computers often include AC to DC power converter circuitry in the form of computer power supply units. A computer power supply unit has a socket that receives an AC power cord. With this type of arrangement, the AC power cord may be plugged directly into the rear of the computer to supply AC power without using an external power converter.
Although desktop computers are large enough to accommodate internal power supplies, other devices such as handheld electronic devices and portable computers are not. As a result, typical handheld electronic devices and laptop computers require the use of external power converters. When disconnected from the power converter, a handheld electronic device or portable computer may be powered by an internal battery. When AC line power is available, the power converter is used to convert AC power into DC power for the electronic device.
Compact AC-DC power converter designs are typically based on switched-mode power supply architectures. Switched-mode power converters contain switches such as transistor-based switches that work in conjunction with energy storage components such as inductive and capacitive elements to regulate the production of DC power from an AC source. A feedback path may be used to tap into the converter output and thereby ensure that a desired DC voltage level is produced under varying loads.
High power converter efficiency is desirable for conserving power. High power conversion efficiency can be obtained by using efficient converter topologies and low-loss parts. Even when an optimal design is used, however, there are residual power losses when operating a power converter. These residual losses are associated with leakage currents and other parasitic effects that arise from running the switched-mode circuitry of the converter and lead to the consumption of power by the power converter even when the power converter is not being used to supply significant amounts of power to an electronic device. Although a user who desires to minimize power losses could manually disconnect a power converter from AC line power when not in use, this type of manual approach is burdensome on the user.
It would therefore be desirable to provide a power converter and electronic device that are able to cooperate with each other in a way that allows power consumption to be minimized without burdening a user.